1. Field of the Invention
The invention relates to a device and method for performing error detection on a digital signal portion, and a receiver and decoding method employing such error detection. In particular, the invention relates to an error detector and method for performing, and a receiver and decoding method which perform, error detection on an interleaved signal portion.
2. Description of Related Art
Digital information signals are often encoded and transmitted through transmission mediums, such as, for example, optical record carriers. Such signals can be digital audio signals representing music, or digital video signals representing full motion video, pictures, or television signals.
A digital information signal is made up of digital information signal portions. Each such digital information signal portion includes information data bytes.
When a digital information signal portion is encoded for transmission through a transmission medium, one or more error detection data bytes are typically added to the information data bytes of that digital information signal portion in a process which produces a coded signal portion. Such a coded signal portion is made up of data bytes which include the information data bytes of a digital information signal portion and the one or more error detection data bytes added thereto. Prior to transmission, the data bytes of a coded signal portion are interleaved (i.e., the coded signal portion is interleaved), producing a corresponding interleaved signal portion having the same data bytes in an interleaved order.
To obtain a replica of a digital information signal portion encoded in the manner just described (and received from a transmission medium), a decoding process including error detection is used. Such a decoding process requires that the data bytes of an interleaved signal portion be de-interleaved (i.e., the interleaved signal portion is de-interleaved), producing a corresponding de-interleaved signal portion having the same data bytes in a non-interleaved order. In the prior art, interleaved signal portions having certain types of error detection data bytes must be de-interleaved prior to error detection because of the manner in which prior art error detectors operate on the appropriate data bytes of such interleaved signal portions.
Accordingly, in the prior art, certain receivers include a de-interleaver connected in cascade with an error detector. Such receivers produce a time delay between when the data bytes of an interleaved signal portion are first available and when error detection can be performed on the appropriate data bytes. This is because the prior art error detector needs to wait for all of the data bytes of an interleaved signal portion to be stored in a de-interleaver and for that de-interleaver to begin reading out those data bytes (producing a corresponding de-interleaved signal portion) before error detection can be performed on the appropriate data bytes.